February 8, 20233 yr Hi All, Any help/advice would be greatly appreciated! Setup: 2x Axpert 5000-48, v74.10 24x 320W panels 42kWh LiFePO4 bank - SolarMD 5kva AVR Honda Generator Last month i had an issue where the battery bank needed a topup (with all the cloudy days we had) so i had to start up the generator. Before i started it i made sure to power down all the outgoing ac loads in order to gradually switch them on and so to increase the loads slowly after the inverters where happy with the genset power. I was standing in front of the inverters when i saw them struggeling to accept the generator power. (Im going to try to explain the best i can in layman's terms what i saw) The inverters where "taking" and "rejecting" the generator (grid input) power a couple of times. This would happen in the past, and eventually the inverters would take the generator power and pass it on to the ac loads via bypass. This time however, after a couple of tries a heard a big bang/pop coming from my master inverter. Sent it in and was told its a damaged main board. Please do note that the system had no ac load at the time and grid charging current was set to 20A on both inverters (that should mean about 1kW draw for battery charging if i have my ducks in a row (20Ax54v)). The generator was also earthed and the cabeling coming from it to the inverters are oversized (2x 2.5mm2 cable leads plugged into both sockes on the generator so to distribute the current draw) Now i would like to know how i can improve my setup so that this wont happen again. Ive been advised to install a SPD (surge protection device) and a frequency filter between the generator and the inverter. Any other recommendations/ advice would really be appreciated Thank you so much!
February 8, 20233 yr Did you set the inverters to take minimal AC charging power initially? Try a running a decently sized load on the Generator you can throttle back like a small power drill. Start genny,give it a minute to heat up,run drill gradually amped up till Generator output throttles up then connect your inverter What tends to happen is the generator throttling up and down surges the power ever so slightly and the inverters disconnect and reconnect constantly as it assumes the grid input is unstable
February 9, 20233 yr Author 22 hours ago, PsyWulf said: Did you set the inverters to take minimal AC charging power initially? Try a running a decently sized load on the Generator you can throttle back like a small power drill. Start genny,give it a minute to heat up,run drill gradually amped up till Generator output throttles up then connect your inverter What tends to happen is the generator throttling up and down surges the power ever so slightly and the inverters disconnect and reconnect constantly as it assumes the grid input is unstable Hi @PsyWulf thank you for taking the time to help me. Do you think if i install a surge protector it will remove this issue completely? Thanks so much!
February 9, 20233 yr All I can suggest is to add a small (100-500 W) load to the generator before connecting it to the inverter. The idea is to stabilise the generator's frequency so that it is easier for the inverter to synchronise to. I'm surprised it blew up though; I can't think of a mechanism / reason.
February 9, 20233 yr 13 minutes ago, Jack007 said: Hi @PsyWulf thank you for taking the time to help me. Do you think if i install a surge protector it will remove this issue completely? Thanks so much! A surge arrestor will probably not help. I suspect the inverter does not like the fluctuating frequency of the generator. Put in a Sunsynk/Deye inverter and then you will be able to limit the generator load. You also can consider running a dedicated 48V charger off the generator. Otherwise more solar and batteries can work
February 9, 20233 yr 3 hours ago, Jack007 said: Hi @PsyWulf thank you for taking the time to help me. Do you think if i install a surge protector it will remove this issue completely? Thanks so much! Quite the opposite,disconnecting and reconnecting is exactly the problem
February 9, 20233 yr 3 hours ago, Jack007 said: Hi @PsyWulf thank you for taking the time to help me. Do you think if i install a surge protector it will remove this issue completely? Thanks so Surge arresters may not be able to absorb the whole power of a surge but can manage as much as 90% of it which is enough to prevent damage to your electronics. The rest of the power surge should be handled by smaller surge protectors in devices. I run a 8kva Turner& Morris diesel silent generator and never had a problem synchronizing with my 8kw Deye inverter. Smaller petrol generators tend to generate harmonics due to flactuations when loading and unloading. I use this double pole surge arrestor in my generator change over switch.
February 10, 20233 yr Author Thank you all for the replies and help 12 hours ago, frivan said: A surge arrestor will probably not help. I suspect the inverter does not like the fluctuating frequency of the generator. Put in a Sunsynk/Deye inverter and then you will be able to limit the generator load. You also can consider running a dedicated 48V charger off the generator. Otherwise more solar and batteries can work @frivan im definitely considering upgrading the whole system do Sunsynk/Deye, but i would like to get a bit more out of the current setup before another big investment is made. Running a dedicated charger was something ive also been thinking about and makes the most sense to me with this system's limitations. Are there any charger brands you can recommend? Ive had a look and it seems victron has some, but they are pricey. Would a frequency filter help? Ive also read up on sinewave filters. - not sure if this would help at all So do i understand correctly that this was more likely a frequency issue than a voltage surge/fluctuation issue causing the inverters to reject the generator's power? 9 hours ago, TaliaB said: Smaller petrol generators tend to generate harmonics due to flactuations when loading and unloading @TaliaB What can i use to help with harmonics? Would a larger diesel generator also solve this problem? (1.5x inverter size?) ive picked up from multiple places that diesel is more stable than petrol - not sure if this is only because they tend to be larger or if there is a different reason for this. Thank you so much all for all the replies and help!
February 10, 20233 yr SANS 10142-1 states in clause 7.12.2.7 that a 230 V generator with a V-O-V earth connection (centre tap on winding which is earthed) shall not be connected to a fixed electrical installation. Such a generator may only be used as a free-standing unit to provide power to specific appliances. If the generator has a tubular frame it is most probably a V-0-V arrangement. To test start your generator and plug a earth leakage tester in if it shows the fault indication ( incorrect wiring) then you know it is a V-0-V arrangement. That is the main reason i bought the Turner & Morrison diesel generator as it is a V-0-0 and legal to connect to your utility power via a changeover switch.
February 10, 20233 yr 3 hours ago, Jack007 said: Running a dedicated charger was something ive also been thinking about and makes the most sense to me with this system's limitations. Are there any charger brands you can recommend? Ive had a look and it seems victron has some, but they are pricey. Would a frequency filter help? Ive also read up on sinewave filters. - not sure if this would help at all So do i understand correctly that this was more likely a frequency issue than a voltage surge/fluctuation issue causing the inverters to reject the generator's power? I have bought a MeanWell charger from CurrentAutomation. I hope that the CAN interface can work with my batteries. But I must still test it. To my knowledge poor generator control primarily shows up in speed/frequency fluctuations. Filters can only assist with harmonics, not changing the supply frequency. So, they won't work for you unless harmonics are affecting the sensing of the frequency.
February 10, 20233 yr Author 2 hours ago, TaliaB said: SANS 10142-1 states in clause 7.12.2.7 that a 230 V generator with a V-O-V earth connection (centre tap on winding which is earthed) shall not be connected to a fixed electrical installation. Such a generator may only be used as a free-standing unit to provide power to specific appliances. If the generator has a tubular frame it is most probably a V-0-V arrangement. To test start your generator and plug a earth leakage tester in if it shows the fault indication ( incorrect wiring) then you know it is a V-0-V arrangement. That is the main reason i bought the Turner & Morrison diesel generator as it is a V-0-0 and legal to connect to your utility power via a changeover switch. Thank you for this. Would this still be applicable if the system is offgrid/no-Eskom? Is it a requirement to legally connect to eskom or is this a general safety rule for the load side?
February 10, 20233 yr It has to do with safety of any electrical installation. If any power generation does not comply to safe earthing standards then you put lives on the line. Sans 10142 is not as such a set of rules to be followed but it applies to safety to the consumer and property. If any generator is connected to Eskom it must be isolated from the grid via a double pole 3 position transfer switch or a Ats( outomatic transfer switch) that breaks live and neutral. Secondly using a V-0-V generator your RCD would not work as designed due to incorrect earhing arrangement. In the event of property any electrical installation or inadequate equipment used you will not be able to obtain a COC and therefore your insurance will not honour the agreement even if it is off grid.
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